A lumber trimmer contains multiple, independently vertically actuable drop saws used to cut lumber into a variety of lengths. The drop saws are fixed in their position along the trimmer. One movable trim saw may be mounted at or near one end of the trimmer. The movable trim saw is vertically and horizontally actuable to trim an end of a board as it passes through the trimmer. In particular, the movable trim saw is a single circular saw that is horizontally incrementally movable so as to trim the end of a board at a point closest to the desired increment. Where the single movable trim saw may be translated laterally over a distance of for example 24 inches, it will be appreciated that the time interval to move the saw from a minimum first end trim (that is, trimming only a small amount off the end of the board) to a second maximum end trim (in the given example ten trimming twenty-four inches off the end of the board) may be relatively lengthy compared to the available time between boards in light of lug speeds approaching 200 lugs per minute typically experienced in conventional lumber handling chain conveyors.
In the prior art applicant is aware of U.S. Pat. No. 5,142,955 which issued Sep. 1, 1992, to Hale for a Lumber Cutter for Removing End Defects and Sawing to Desired Lengths. This application discloses a unitary drop trim saw mounted at the root edge of a lumber conveyor. The drop trim saw may be selectively vertically articulated into or out of the path of lumber carried by the conveyor. The trim saw is horizontally slidable into the lumber path in ½ inch increments over a 24 inch distance, in order to cut defects from the end of a board.
The present invention includes selective lateral translation of a pair of independently actuable end trim saws, mounted for concurrent co-axial transverse reciprocal movement at the end of a trimmer, thus minimizing the horizontal translation distance of the saws from a first minimum trimming position to a second maximum trimming position. The time required for lateral translation between these two positions is thereby reduced, which increases efficiency, for example by avoiding a reduction in lumber handling speeds.
In the current invention, the trim saws has a fixed spacing between them of, for example, 12 1/16 inches, and are vertically actuable by suitable pneumatic means so as to selectively cut lumber to the desired length as it passes through the trimmer. For example, when cutting a 16-foot board, the most valuable use is to cut it into custom stud lengths, such as 92⅝ inches. Using trim saws of fixed spacing, two 8-foot boards are normally produced as the larger board passes through the trimmer. A stud is produced at the ‘lumber’ line end of the trimmer where a movable precision end trim saw is employed. The 8-foot (96 inch) length remaining on the opposite ‘clear’ line end remains as a dimensioned lumber piece unless further trimming is available. The substitution of the last two saws in a 16-foot trimmer with a pair of laterally movable trim saws, such as those of the present invention, allows for greater flexibility in the lumber trimming process. In sawmills where metric and other lumber sizes are produced, laterally movable trim saws provide ease of trimming to the required length.
It is therefore an object of the present invention to provide a lumber trimmer with at least one pair of laterally movable, independently actuable trim saws positioned at one or both ends of the trimmer to facilitate additional trimming of the lumber.
It is a further object of the present invention to provide a lumber trimmer which can produce a variety of lumber lengths irrespective of the fixed trim saw spacing.